1. Field of the Invention
The present invention relates to an externally adjustable RF impedance matching mechanism and more particularly, to a dexterously constructed RF substrate layout and impedance matching mechanism design enable to manual adjust the impedance value from outside of the enclosure.
2. Description of the Prior Art
In supplying electric power from a source to a load with a favorable impedance matching state, it is important to use an effective impedance network or mechanism. Thereby adjusting the line inductance to match the load capacitance in the most optimistic condition is the crucial task for the RF power transmission.
In a conventional impedance matching structure shown in FIG. 4, a circuit element 81 with its board is mounted on a base 82, and a lid 83 covers over the base 82 containing the circuit 81 therein. The circuit element 81 including its substrate in one unit is enclosed by ceramic material so as to easily dissipate the heat generated by the power transmission through its impedance matching circuit and protects the element 81 from thermal destruction. But by so the production cost is high.
Besides, the circuit element 81 constructed as such is then secured mounting to the base 82 with fixing saddles 84 at two sides thereof such that the electric board entraining the circuit element 81 will be deformed owing to thermal expansion. Further, such thermal expansion of the circuit board leads to loosening of the engagement between the circuit board and the thermal conductive base 82. As a result, from worse to worst, the accumulated heat inside the circuit element 81 raises up the temperature to the extent causing cracks in the inductance coil portion of the ceramic substrate shown in FIG. 5.
Such is the case that is always experienced by any conventional product. Therefore, aiming at the above depicted defects, the present invention is to propose a newly urbanized externally adjustable RF impedance matching mechanism capable of operating at high power with better impedance coupling result.